The infection of cells by the human immunodeficiency virus (HIV) is effected by a process in which the membrane of the cells to be infected and the viral membrane are fused. A general scheme for this process is proposed: The viral envelope glycoprotein complex (gp120/gp41) interacts with a cell surface receptor located on the membrane of the cell to be infected. The binding of gp120 to, e.g., the CD4 receptor in combination with a co-receptor such as CCR-5 or CXCR-4 causes a change in the conformation of the gp120/gp41 complex. In consequence of this conformational change the gp41 protein is able to insert into the membrane of the target cell. This insertion is the beginning of the membrane fusion process. It is known that the amino acid sequence of the gp41 protein varies in different HIV strains because of naturally occurring polymorphisms. But the same domain architecture can be recognized, more precisely, a fusion signal, two heptad repeat domains (HR1, HR2) and a transmembrane domain (in N- to C-terminal direction). It is suggested that the fusion (or fusogenic) domain is participating in the insertion into and the disintegration of the cell membrane. The HR regions are built up of multiple stretches comprising seven amino acids (“heptad”) (see e.g. W. Shu, et al., Biochem (1999) 38:5378-85). Beside the heptads one or more leucine zipper-like motifs are present. This composition accounts for the formation of a coiled coil structure of gp41 proteins and just as well of peptides derived from these domains. Coiled coils are in general oligomers consisting of two or more interacting helices. Peptides with amino acid sequences deduced from the HR1 or the HR2 domain of gp41 are effective in vitro and in vivo inhibitors of HIV uptake into cells (for example peptides see e.g. U.S. Pat. No. 5,464,933, U.S. Pat. No. 5,656,480, U.S. Pat. No. 6,258,782, U.S. Pat. No. 6,348,568, or U.S. Pat. No. 6,656,906). For example, T20 (also known as DP178, Fuzeon®, a HR2 peptide), T651 (U.S. Pat. No. 6,479,055), and T2635 (WO 2004/029074) are very potent inhibitors of HIV infection. It has been attempted to enhance the efficacy of HR2 derived peptides with, for example, amino acid substitutions or chemical crosslinking (S. K. Sia, et al., Proc. Natl. Acad. Sci. USA (2002) 99:14664-69; A. Otaka, et al., Angew. Chem. Int. Ed. (2002) 41:2937-40).
The conjugation of peptides to certain molecules can change their pharmacokinetic properties, e.g. the serum half-life of such peptide conjugates can be increased. Conjugations are reported, for example, for polyethylene glycol (PEG) and Interleukin-6 (EP 0 442 724), for PEG and Erythropoietin (WO 01/02017), for chimeric molecules comprising Endostatin and immunoglobulins (US 2005-008649), for secreted antibody based fusion proteins (US 2002-147311), for fusion polypeptides comprising albumin (US 2005-0100991; human serum albumin U.S. Pat. No. 5,876,969), for PEGylated polypeptides (US 2005-0114037), and for interferon fusions. Also described in the state of the art are immunotoxins comprising Gelonin and an antibody (WO 94/26910), modified transferrin-antibody fusion proteins (US 2003-0226155), antibody-cytokine fusion proteins (US 2003-0049227), and fusion proteins consisting of a peptide with immuno-stimulatory, membrane transport, or homophilic activity and an antibody (US 2003-0103984). In WO 2004/085505 long acting biologically active conjugates consisting of biologically active compounds chemically linked to macromolecules, are reported.
The co-receptor CCR5 is used by most HIV-1 primary isolates and is critical for the establishment and maintenance of infection. In addition, CCR5 function is dispensable for human health. A mutant CCR5 allele, “CCR5Δ32”, encodes a truncated, non-functional protein (M. Samson, et al., Nature (1996) 382:722-25; M. Dean, et al., Science (1996) 273:1856-62). Individuals homozygous for the mutation lack CCR5 expression and are strongly protected from HIV-1 infection. They demonstrate no overt phenotype consequence and are highly resistant to M-tropic HIV infection, whereas heterozygote individuals present delayed disease progression (M. K. Schwarz and T. N. Wells, Nat. Rev. Drug Discov. (2002) 1:347-58). The lack of CCR5 is without apparent adverse consequences, probably because CCR5 is part of a highly redundant chemokine network as receptor for the α-chemokines MIP-1α, MIP-1β, and RANTES, which share many overlapping functions, and most of which have alternative receptors (D. Rossi and A. Zlotnik, Ann. Rev. Immunol. (2000) 18:217-42). The identification of CCR5 as an HIV-1 co-receptor was based on the ability of its ligands, MIP-1α, MIP-1β, and RANTES, to block infection by R5 but not R5X4 or X4 isolates (F. Cocchi, et al., Science (1995) 270:1811-15). CCR5 is also a receptor of the “cluster” chemokines, which are produced primarily during inflammatory responses and control the recruitment of neutrophils (CXC chemokines), macrophages and a subset of T cells (T helper Th1 and Th2 cells). Th1 responses are typically those involving cell-mediated immunity effective against viruses and tumors, proinflammatory responses responsible for killing intracellular parasites, and perpetuating autoimmune responses, for example, whereas Th2 responses are believed to be pivotal in allergies. Therefore, inhibitors of these chemokine receptors may be useful as immunomodulators. For Th1 responses, overactive responses are dampened, for example, in autoimmunity including rheumatoid arthritis, or, for Th2 responses, asthma attacks or allergic responses including atopic dermatitis are lessened (see e.g. D. Schols, Curr. Top. Med. Chem. (2004) 4:883-93; A. Mueller and P. G. Strange, Int. J. Biochem. Cell Biol. 36:35-38; W. M. Kazmierski et al., Curr. Drug Targets Infect. Disord. (2002) 2:265-78; T. Lehner, Trends Immunol. (2002) 23:347-51).
Antibodies against human CCR5 are e.g. PRO140 (W. C. Olson et al., J. Virol. (1999) 73:4145-55), and/or 2D7 (M. Samson et al., J. Biol. Chem. (1997) 272:24934-41). Additional antibodies are mentioned in US 2004-0043033, U.S. Pat. No. 6,610,834, US 2003-0228306, US 2003-0195348, US 2003-0166870, US 2003-0166024, US 2003-0165988, US 2003-0152913, US 2003-0100058, US 2003-0099645, US 2003-0049251, US 2003-0044411, US 2003-0003440, U.S. Pat. No. 6,528,625, US 2002-0147147, US 2002-0146415, US 2002-0106374, US 2002-0061834, US 2002-0048786, US 2001/0000241, EP 1 322 332, EP 1 263 791, EP 1 207 202, EP 1 161 456, EP 1 144 006, WO 2003/072766, WO 2003/066830, WO 2003/033666, WO 2002/083172, WO 02/22077, WO 01/58916, WO 01/58915, WO 01/43779, WO 01/42308, and EP 05007138.0.
Polyethylene glycol conjugates of antibodies against CCR5 are known from US 2003-0228306. US 2003-0215421 refers to chemokine-toxin conjugates. WO 01/43779 refers to conjugates of anti-CD4 antibodies and anti-CCR5 antibodies and to conjugates of anti-CD4 antibodies and an HIV-1 fusion inhibiting peptide. Conjugates of CCR5 antibodies and toxins are mentioned in EP 1 346 731.